Physical disability is a serious and frequent consequence of the burden of chronic disease and physiologic changes associated with aging. With the aging of the U.S. population, there is increasing concern to understand how to decrease this burden of disability, preventing both its onset and progression. To develop effective methods for primary prevention of disability, it is necessary to define those at risk of disability, as well as its causes. To these ends, this study proposes, first, to identify early decrements in physical functioning in women 65 years and older, termed "preclinical disability," and to demonstrate whether these changes identify those at high risk of becoming disabled and are predictive of future disability. Second, we will evaluate the diseases that are risk factors for the onset of preclinical disability and its progression to full-fledged disability and dependency, as well as the hypothesized modifiers of this relationship. This will be addressed through a longitudinal, observational study involving three examinations (at 18 month intervals) of 600 women 70-79 years of age. These women will be recruited from a representative, racially diverse, population-based sample of 5,500 women 65 years and older in Eastern Baltimore during screening for the Women's Health and Aging Study; this latter study will recruit the 1,000 most disabled women. We propose to utilize this already-funded effort to recruit for this study 600 women who are non-disabled, and in the high risk age group for becoming disabled. They will be evaluated in the Johns Hopkins Functional Status Laboratory, in a one-day multidisciplinary examination of physical function as measured by self-report and performance-based measures of preclinical and clinical disability, health status (measured by self-report and laboratory-based examination) - both disease-based and physiologic changes of aging; and hypothesized modifiers of function, including cognition, education and psychosocial function. Natural history of preclinical disability, the development of disability and the risk factors for transitions in functional status will be analyzed cross-sectionally and longitudinally. The results of this study will help to define those older women at risk of disability, and the potentially alterable risk factors that could be developed into effective interventions to prevent disability in aging women.